Linear discriminant analysis for improved large vocabulary continuous speech recognition

  • Authors:
  • R. Haeb-Umbach;H. Ney

  • Affiliations:
  • Philips Research Laboratory Aachen, Aachen, Germany;Philips Research Laboratory Aachen, Aachen, Germany

  • Venue:
  • ICASSP'92 Proceedings of the 1992 IEEE international conference on Acoustics, speech and signal processing - Volume 1
  • Year:
  • 1992

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Abstract

The interaction of Linear Discriminant Analysis (LDA) and a modeling approach using continuous Laplacian mixture density HMMs is studied experimentally. The largest improvements in speech recognition accuracy could be obtained when the classes for the LDA transform were defined to be sub-phone units. On a 12,000-word German recognition task with small overlap between training and test vocabulary a reduction in error rate by one fifth was achieved compared to the case without LDA. On the development set of the DARPA RM1 task the error rate was reduced by one third. For the DARPA speaker-dependent nogrammar case, the error rate averaged over 12 speakers was 9.9%. This was achieved with a recognizer employing LDA and a set of only 47 Viterbi-trained contextindependent phonemes.